A recording and/or reproducing apparatus employing a tape cassette housing a magnetic tape as a recording medium is currently in use. As this sort of the recording and/or reproducing apparatus, there is known an audio PCM tape recorder or a video tape recorder having a rotary magnetic head device which is comprised of a rotary magnetic head having sliding contact with the magnetic tape pulled out of the tape cassette, or a tape guide drive.
In this recording and/or reproducing apparatus, information signals are recorded and/or reproduced for a magnetic tape by causing the rotary magnetic head to have a sliding contact with the magnetic tape run from or to a tape guide drum.
The recording and/or reproducing apparatus having the rotary magnetic head device is provided with a tape loading mechanism for pulling out the magnetic tape housed in the tape cassette for being taken up on a tape guide drum after running on a pre-set tape running path in the main body unit of the apparatus. The tape loading mechanism has a movement guide block which is moved between the tape cassette loading mechanism and the rotary magnetic head device. This movement guide block has a guide roll about which the magnetic tape is hooked so as to be pulled out of the tape cassette and so as to be automatically loaded on the tape running route. The magnetic tape wound about the tape guide drum is run at a constant velocity as it is clinched between a capstan arbor run in rotation by a capstan motor and a pinch roll.
Meanwhile, in a recording and/or reproducing apparatus, such as an audio PCM tape recorder having a rotary magnetic head device, there are occasions wherein the magnetic tape is run in a direction reversed for the forward direction for recording and/or reproducing information signals for the magnetic tape as when retrieving the signals recorded on the magnetic tape or re-writing sub-codes.
For doing these operations, this sort of the tape recorder includes a mechanism for selectively driving supply side or take-up side reel shafts depending on the tape running direction. The mechanism for switching between the reel shafts to be in operation depending on the tape running direction is adapted for transmitting the driving force of the reel shaft driving motor to one of the reel shafts, and is provided independently of the capstan motor adapted for running the magnetic tape at a constant velocity.
With the recording and/or reproducing apparatus having the capstan motor for running the magnetic tape at a constant velocity and the driving motor for driving the reel shaft, the capstan motor and the reel shaft driving motor can be controlled independently of each other, and hence the magnetic tape can be taken up simultaneously with switching of the running direction of the magnetic tape, thus assuring prompt switching of the tape running direction.
With this sort of the recording and/or reproducing apparatus, the following inconvenience arises when accommodating the magnetic tape pulled out on the tape running route in the tape cassette by way of unloading for taking out the tape cassette from the cassette loading unit in the main body unit of the apparatus.
For loading the magnetic tape on a pre-set tape running route, the magnetic tape is pulled out of the tape cassette. It is therefore necessary for the driving force transmitting gear transmitting the driving force of the reel shaft driving motor to the supply side reel shaft not to mesh with the supply side reel shaft. For unloading the magnetic tape, it is necessary for the driving power transmitting gear to be engaged with the supply side reel shaft.
Since the driving power transmitting gear is engaged with the reel shaft when the tape cassette is ejected from the cassette loading unit in the main body unit, it is necessary to separate the driving power transmitting gear meshing with the supply side reel shaft from the reel shaft when loading the tape cassette on the cassette loading unit for loading the magnetic tape on the pre-set tape running route. With this sort of the recording and/or reproducing apparatus, such a mechanism is required which is adapted for spacing the driving power transmitting gear from the reel shaft for loading the magnetic tape from the unloaded state, thus complicating the structure of the tape loading mechanism.
Moreover, if a large amount of the magnetic tape is wound on a tape reel, the winding diameter is increased, thus raising the tape take-up speed. Conversely, if a small amount of the magnetic tape is wound on a tape reel, the winding diameter is decreased, thus lowering the tape take-up speed. Thus, it may be feared that, depending on the winding state of the magnetic tape on the tape reel, the speed with which the magnetic tape is taken up on the tape reel becomes faster than the speed with which the movable guide block constituting the tape loading mechanism of the magnetic recording and/or reproducing apparatus is moved from the loading position laterally of the rotary magnetic head device to the tape cassette loading position, thus possibly imposing tension larger than is necessary on the magnetic tape to destroy the tape.
On the other hand, the recording and/or reproducing apparatus, employing the tape cassette as a recording medium and which is provided with a rotary magnetic head device, includes a tape cassette transfer member or a cassette holder supported for movement across the tape cassette loading/unloading position and the tape cassette loading position. The tape cassette is moved via the tape cassette transfer member or the cassette holder to the tape cassette loading position so as to be loaded on the cassette loading unit of the main body portion of the recording and/or reproducing apparatus.
The magnetic tape pulled out of the tape cassette is wound about the tape guide drum a pre-set angular extent to achieve sliding contact with the rotary magnetic head. Thus, the running route of the magnetic tape is of a complex shape, being of a substantially M- or U-shape about the rotary magnetic head as center. The recording and/or reproducing apparatus has the above-mentioned tape loading mechanism for loading the magnetic tape on this complex tape running route.
Meanwhile, in a recording and/or reproducing apparatus, reduced to a portable size, the apparatus in its entirety is small-sized, so that component parts of the tape loading mechanism are spaced apart from one another an extremely small distance, that is, these component parts are proximate to one another. Thus, the movable guide block, constituting the tape loading mechanism, is located extremely close to the rotary magnetic head device when the guide block is moved to close to the magnetic head device. Also, the movable guide block is mechanically supported by a supporting arm supporting it, so that, by the supporting arm making its rotation, the movable guide block is moved between the tape cassette loading position and the rotary magnetic head position. Since the movable guide block is mechanically supported as described above, it has some allowance, so that, if it is moved to close to the rotary magnetic head device, the risk is high that the guide block is tilted towards and occasionally contacted with the rotary magnetic head.
If the magnetic tape recording and/or reproducing apparatus, having the above-mentioned rotary magnetic head device, is in the recording/reproducing mode of recording/reproducing information signals, the pinch rolls are pressed against a capstan, and hence the magnetic tape is clinched therebetween and run at a constant velocity. If the apparatus is in the fast-feed mode, the pinch roll is spaced apart from the capstan, while the supply side reel, operating as the tape supply side, is set so as to be rotatable freely. The take-up side reel is rotated at a high velocity by a reel driving motor for running the magnetic tape at an elevated speed in order to take up the tape on the take-up side reel. If the apparatus is in the rewind mode, that is in a mode of rewinding the magnetic tape once taken up on the take-up roll, the pinch roll is spaced apart from the capstan, while the take-up side reel, operating as the tape supply side, is set so as to be rotatable freely. The supply side reel is rotated at a high velocity by the reel driving motor for running the magnetic tape at an elevated speed in order to rewind the tape on the supply side reel.
Meanwhile, if, in the recording/reproducing apparatus having the conventional rotary magnetic head device, the running of the magnetic tape is to be halted during fast feed or rewind operations, the driving current to the reel driving motor is turned off, at the same time as a braking unit, such as a braking pad, is applied against a portion of a mechanism for transmitting the driving power of the driving motor to the reel, in order to prevent the take-up side reel or the supply side reel from being rotated by the force of inertia of the driving motor notwithstanding the interruption of the driving current.
There is also such a recording/reproducing apparatus in which, instead of providing a forced braking mechanism, such as brake pad, the braking current opposite in direction to that of the driving current during the fast feed mode or rewind mode is supplied to the reel driving motor for applying an abrupt braking action to the reel driving motor.
If a large amount of the magnetic tape is wound on the tape reel set to a rotatable state, the tape reel keeps on to be rotated by its force of inertia to reel out the magnetic tape, no matter whether the rotation of the reel driving motor is halted by the above-mentioned braking mechanism or by the control current. The result is that the magnetic tape is slackened on cessation of the fast feed or rewind operations.
In the magnetic tape recording and/or reproducing apparatus adapted for halting rotation of the reel driving motor by the control current, it may be contemplated to decrease the control current gradually to prevent the magnetic tape from being slackened, that is to lower the voltage of the braking current applied to the coil of the reel driving motor, for gradually braking the reel driving motor. However, with the reel driving motor, the braking applied to the driving motor is strong so that the magnetic tape cannot be prevented from becoming slackened even if the voltage of the braking current is lowered gradually.